function [ status ] = mx_eyelink_poll_responses( )
%MX_EYELINK_POLL_RESPONSES Returns the count of node addresses received so 
% far following the call of eyelink_poll_remotes() or eyelink_poll_trackers().
%
% Remarks:
% You should allow about 100 milliseconds for all nodes to respond. Up to 4 node responses are saved.
% Returns:
% Number of nodes responded. 0 if no responses.
%
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% Copyright Eduardo Aponte 2013
% aponteeduardo@gmail.com